JPS5916693B2 - Method for forming conductive film on optical lens for projection type cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a conductive layer for an optical lens for a projection type cathode ray tube, which makes it possible to form a strong conductive layer on the optical lens in a short time.

For cathode ray tubes, such as projection type cathode ray tubes, which have an optical lens built into the tube, if a charging phenomenon occurs in the optical lens, the potential distribution in the vicinity changes, causing problems such as disturbing the trajectory of the electron beam. Forms a conductive layer.

FIG. 1 shows a meniscus lens 1 used in this type of projection type cathode ray tube. Since a fluorescent surface target 3 placed in an aperture 2 is scanned by an electron beam, the scattered electrons of the electron beam and the fluorescent surface target 3 are The secondary electrons flow into the outer surface 4 of the meniscus lens 1, a charging phenomenon occurs on the outer surface 4, and the potential distribution near the fluorescent surface target 3 is slightly disturbed.The electron beam trajectory is determined and the image is changed. This causes problems such as misalignment and distortion.

In order to avoid such drawbacks, a conductive layer is formed in advance on the side of the meniscus lens 1 from which the electron beam comes, that is, before the fluorescent surface target 3 is provided on the outer surface 4.

This conductive layer is often made of indium vapor-deposited under high-temperature heating in order to be optically transparent, mechanically strong, and strong enough not to be easily peeled off.

However, since the meniscus lens 1 is bowl-shaped, distortion will occur and the lens glass will break unless the heating and lowering of the temperature for high-temperature deposition are carried out gradually and slowly during vacuum deposition.

Furthermore, if the shape of the heat source for heating is not similar to a bowl shape, it will be difficult to evenly heat and raise the temperature, and this will also impose a constraint that the temperature must be raised and lowered slowly.

Furthermore, it is even more difficult to provide a heat source to simultaneously vacuum-deposit a large number of meniscus lenses 1 in a vacuum chamber. Firstly, it requires a long working time, and secondly, it is difficult to provide a heating source.

Thirdly, there is a drawback that it is difficult to deposit a large number of layers at the same time.

Furthermore, fourthly, it is very difficult to arrange the vapor deposition source so as to form a uniform vapor deposited film on a curved surface because the meniscus lens 1 has a special bowl-shaped shape.

In particular, when using a large number of lenses at the same time, it is particularly difficult to arrange the vapor deposition sources so as to form a uniform vapor deposition film.

In order to overcome these drawbacks, recently developed coating methods have been known in which a strong film is formed by sputtering or ion blasting.

These methods require that the object to be coated be a conductor such as a metal, and it is inherently impossible to coat an insulator such as glass, and even if it is possible, special ingenuity is required for the evaporation source. However, there are disadvantages in that there are limitations on the shape of the object to be coated.

The present invention was made to eliminate such drawbacks and limitations, and includes a bowl-shaped mesh that is brought into close contact with a bowl-shaped optical lens for a projection type cathode ray tube, and the bowl-shaped mesh used as an electrode.
The purpose is to form a conductive layer on the optical lens by ion blating.

FIG. 2 is an explanatory diagram for explaining one embodiment of the present invention.

In FIG. 2, the meniscus lens 1 is closely attached to a mesh electrode 5 formed to match the bowl shape of the meniscus lens 1, and the mesh electrode 5 is placed facing an indium evaporation source 6.

The DC high voltage power supply 7 has its - (minus) side connected to one end of the mesh electrode 5, and its + (plus) side connected to one of the heater lead wires 8 of the indium evaporation source 6.

In such a configuration, the exhaust system is operated to exhaust the inside of the bell jar 9, and then an inert gas such as argon is introduced.

Then, in this atmosphere, the evaporation source 6 is energized to evaporate indium.

In this case, since the mesh electrode 5 is bowl-shaped, the electric field (or lines of electric force) formed by the high voltage applied to the mesh electrode 5 corresponds to the bowl shape as shown in the line group shown in the figure. Meniscus lens 1
is assumed to be perpendicular to the surface of

Since the electric field is in this state, the evaporated indium collides with the argon gas molecules to form an ion flow, and is accelerated while riding in the direction of the electric field at right angles to the surfaces of the mesh electrode 5 and the meniscus lens 1. to shoot at.

Since the mesh electrode 5 is in close contact with the meniscus lens 1 in a bowl-shaped manner, ion penetration is even and strong throughout the mesh electrode 2 and the meniscus lens 1, and in this way, the indium is transferred to the back side of the mesh. The mesh electrode 5 functions not only as an electrode but also as a reinforcing core material for the conductive layer and as a conductor. , it has even better conductivity and can strengthen the conductive layer.

Furthermore, unlike the conventional method, there is no need for any thermal process, so the conductive layer can be formed in an extremely short time.

In this embodiment, one meniscus lens 1 is placed inside the bell jar 9, but if a plurality of meniscus lenses 1 can be stored in the space inside the bell jar 9, many meniscus lenses 1 can be placed at the same time. On the other hand, it is also extremely easy to form a conductive layer.

As described above, according to the present invention, a conductive layer is formed on the optical lens by ion blating using a bowl-shaped mesh that is closely attached to a bowl-shaped optical lens for a projection type cathode ray tube as an electrode. Because of this, even though the optical lens has a special bowl shape, it is possible to form a strong conductive layer in a very short time.
A uniform and strong conductive layer can be formed on the lens surface without having to arrange the evaporation source to correspond to the special bowl shape of the optical lens.

This is effective for a large number of lenses.

In particular, since the mesh electrode is bowl-shaped, it not only functions as an electrode, but also as a reinforcing core material for the conductive layer and as a conductor, making the conductive layer extremely strong and highly conductive. It will be excellent.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a meniscus lens and a fluorescent surface target built into a projection type cathode ray tube, and FIG. 2 is an explanatory view for explaining one embodiment of the present invention. In the figure, 1 is a meniscus lens, 5 is a mesh electrode, 6 is an evaporation source, and 7 is a high voltage power source. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An optical lens for a projection type cathode ray tube, characterized in that a bowl-shaped mesh is brought into close contact with a bowl-shaped optical lens for a projection type cathode ray tube, and a conductive layer is formed on the optical lens by ion blating using the bowl-shaped mesh as an electrode. Conductive layer formation method.